**5. Conclusion**

In this research, we proposed a low-leakage dual-plate waveguide and demonstrated the results of evaluating long-distance communications using this waveguide. As a result of this evaluation, under the conditions of *x* = 300 mm and *y* = 400 mm, it was shown that communication was possible at speeds of 100 Mbps or more up to a distance of 92 m. We will continue to consider using this system in tunnels.

### **Acknowledgements**

I am grateful to Dr. Patrick Steglich of the book editor who gave me the opportunity to write this chapter. We thank Mr. Nobuyuki Watanabe and Mr. Toshifumi Sakai (FURUNO) for their help in this study. Moreover, I respect the great achievements of my predecessors whose studies I have cited.

As a result of laying the waveguide over 120 m and measuring the power with the spectrum analyzer located at the end, it was found that the loss was 35.8 dB, i.e., approximately 0.32 dB/m. The output frequency was 5.6 GHz and the bandwidth was 40 MHz. **Figure 21** shows the evaluated throughputs and S/N ratios for the conditions *x* = 300 mm and *y* = 400 mm. In the circumference of the waveguide, good communications were possible up to 93 m. **Table 2** shows the results at *z* = 21 m and **Table 3** shows the results at *z* = 81 m. A S/N ≥ 5 dB was the approximate index for

*Electromagnetic Propagation and Waveguides in Photonics and Microwave Engineering*

communications, and this index provided good communications.

*Throughput and S/N evaluation results (*x *= 300 mm and* y *= 400 mm).*

**Figure 21.**

**94**

**Figure 20.**

*Experimental configuration.*

**References**

**12**(1):36-45

2015;**16**(5):2393-2405

Letters. 2013;**12**:741-744

in a realistic subway tunnel

1723-1732

2005-2014

**97**

[1] Li J, Zhao Y, Zhang J, Jiang R, Tao C, Tan Z. Radio channel measurements and analysis at 2.4/5 GHz in subway tunnels, China. Communications. 2015;

*DOI: http://dx.doi.org/10.5772/intechopen.92246*

European Microwave Conference.

[10] Ishino S, Etani S, Matsumoto S. Study of a 5 GHz dual-plate leakage waveguide for wireless LAN

infrastructure construction. IEICE Tech. Rep. AP2018–37. 2018;**118**(103):1-4

September 1978

*Long-Distance and Low-Radiation Waveguide Antennas for Wireless Communication…*

[Japanese]

[2] Guan K, Ai B, Zhong ZD, et al. Measurements and analysis of largescale fading characteristics in curved subway tunnels at 920 MHz, 2400 MHz, and 5705 MHz. IEEE Transactions on Intelligent Transportation Systems.

[3] Guan K, Zhong ZD, Ai B, et al. Complete propagation model in tunnels. IEEE Antennas & Wireless Propagation

[4] Guan K, Zhong ZD, Alonso JI, Rodriguez CB. Measurement of

distributed antenna systems at 2.4 GHz

environment. IEEE Transactions on Vehicle Technology. 2011;**61**(2):834-837

[5] Wang JH, Mei KK. Theory and analysis of leaky coaxial cables with periodic slots. Institute of Electrical and Electronics Engineers. 2001;**49**(12):

[6] Morgan SP. Prediction of indoor wireless coverage by leaky coaxial cable using ray tracing. IEEE Transactions on Vehicular Technology. 1999;**48**(6):

[7] Ishino S. Novel waveguide technologies and its future system applications, surface waves. In: New Trends and Developments. Croatia:

IntechOpen; 2017. pp. 1-15

Transactions on Antennas and Propagation. Oct. 1959;**7**(4):307-319

[8] Goldstone L, Oliner A. Leaky-wave antennas I: Rectangular waveguides. IRE

[9] Menzel W. A new travelling wave antenna in microstrip. In: 1978 8th
